Electric switch.



J. DBSMOND.

ELECTRIC SWITCH. APPLICATION HLED Mums, 1912.

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Patented M0124, NM,

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-below a predetermined value.

VUNITED STATES PATENT OFFICE.'^ Y

JOHN DESMOND, OF CHICAGO, ILLINOIS, SSIGNOR 'IOXWILLIAM S. POTWIN, 0F

CHICAGO- ILLINOIS.

ELECTRIC SWITCH.

Specification of Letters Patent. APatented Nov,k 24, 1914,

Applicati'n mea March 25, 1912. serial No. 685,941.

To all whom it may 'concern' Be it known ythat I, JOHN DEsMoND, a citizen of the United States, residing at Chicago,'in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Electric Switches, of which the following is a spe ification.

My invention relates to au omatic electric switches.' 'Y

One of the objects of .my invention is to provide a switch adapted to be placedin' circuit with an electric motor adapted to be automatically opened upon the occurrence of a rise of pressure within a receptacle and to be automatically closed when the pressure falls below a. predetermined value.

Ininstances lwhere an electric motor is used to operate an air pump to compress air within a receptacle wherein it is desired to maintain the pressure within certain limits hile the air therefrom is drawn intermitently, it is of economical advantage to automatically stop the motor when the desired pressure has been reached and to start the motor again when the pressure has fallen Such examples are in the use of air operated car brakes; charging tanks for pneumatic tires, and @in many other vsituations that will readily occur to persons skilled in the art.

In the illustrative.exemplification; Figure 1 is an elevation, partly in section, showing my switch; Fig. 2, is a vertical, central, vsection taken on line 2-2 of Fig. 1; Fig. 3

is a plan view of the device.; Fig. 4 is an enlarged air valve detail; Figs. '5 and 6 are details for adjusting the vertical position of the air valve and the extent of its lost motion.

In lall of the views y, the same reference characters indicate similar parts.

The base casting 10 is a means whereby the device may be secured to a support. It is centrally bored'and screw threaded, as at 11, thereby providing an aperturev 12. A. lateral boss 13, preferably an integral part of thebase casting, projects from the central hub 14, at one side of the radial l1m1t of the disk l5. A .perforation 16 isgenlarged at its outer end and isscrew-threaded as at 17 for a pipe 18. The opening 16`-per mits communication from Vpipe 18 to the central opening 12. A^bottom disk 19 with the top disk 20 provides aldiaphragm casing for a diaphragm 21, which 1s secured at its 'edges between said disks and firmly hubs 22 and 26, respectively," said hubs are exteriorly screw-threaded, as at 24 and 25. The hub 26 is interiorly screw-threaded, as

at 27 ,ior valve controlling, axially movable plugs 28 and 29. The plug 28 is screwthreaded, as at 30' and 31, interiorly to permit longitudinal movement of Ythe threaded plug 29 therein and exteriorly for engagement with the screw threads 25 of the hub 26. The plu 28 issplit, as at 32, so as to increase the? the screw-threaded aperture in which it is contained, that-it may\ remain undisturbed in the position to which it may be moved.

An air valve stem 33, is provided with 'a head 3'4, which is smaller iny diameter than the plug 29, and is adapted to pass through the aperture 35 in the plug 28. A shoulder 36 prevents lthe head 34 from passing through the smaller bore 35. The stem is axially perforated, as at 37, and transversely7 split, as at 38, to permit air coming through the pipe 18 to enter the space iny the diaphragm casingibelow the diaphragm. The stem 33 is also provided with a transriction between said plug and :soL

verse bore, as at 39, that intersects the cenf i within lthe hub 22, surrounds the stem 41.

and seats yon a shoulder at the lower end thereof. It is the means for holding the valve seat of the stem 41 on the valve 40 thereby -to shut ofcommunication between the bores 43 and 44:f A cap 46 has screw- `threaded engagement withthe hub 22 for adjusting lthe tension of the spring 45 upon the diaphragm 21, thereby to vary the pressure at which the switch will operate, The.'

cap is also centrally bored and guide for the stem 41.

From the foregoing description it will be understood th at when' the air pressure below the diaphragm dominates the, effect of the;

spring 45, lthat the stem 41 will be lifted and thereby separates the valve 40v from its seat,

permitting air to enter the bore 43, from the source of air supply coming through the pipe '18. l

The split, 38, in the stem 33,A permits yielding expansion ofthe stem 33, so that friction between it and its surrounding inclosure in the stem 41 causes the stem 33 to move with the stem 41 until the head 34 Strikes the shoulder 36 in the plug 28, when further movement of stem 41 in an upward direction opens the air valve 40. Thus the extent of vertical space between the shoulder 36 and theplug 29, within which the head 34 of the stem 33 has lost motion movement, is the means of varyingthe difference in pressure at which the electric motor circu1t will be closed and opened. A 'cap 47 1s centrally bored and is attached to the stemA 41. On its upper end it carries a casting 48, which is axially bored, as at 49 for a piston 50 that moves freely therein.

A casing 51 is secured by screws to lug 52 rising from disk 20. In the upper end of the casing is secured, as by screws 53, a disk 54 of insulating'm'ateriah such as porcelain or the like, and mounted on said disk are two segment-shaped pieces of carbon 55 and -56 interiorly tapered as at 57, and constituting the stationary terminal electrodes of the switch. Screws 58 and 59 take through the disk 54 and are countersunk in the blocks 55 and 56 respectively, and on their lower threaded ends carry nuts 60 and 61, respectively, by which conducting wires 62 and 63 may be connected. The casing 51 is perforated as at 64 and 65 to admit said wires.

A carbon plug 66 is tapered for contact with thetapered surfaces of the terminals 55 and 56, .and when in place, as shown yin the drawings, serves to close the electric circuit therebetween. Said vplug is mounted on an insulating support 67 and secured thereto by the nut 68. Interior of the insulating Y support is a metallic cup 69.

A stem 7 carries on its lower end a' collar 71 thatv guides the stem in the hollow piston 5() and serves as an abutment for the v open-coiled spring 72, that `abuts against the bottom of said hollow piston, and yieldingly holds it in the bottom of the bore 49.

A permanent magnet consisting of the limbs 73 and 74 and a yoke 75, is secured to the casting 48, as by screws 76. A keeper 77 consisting of an iron washer is held in lace by nuts 78-7 9 on the stem 70. vThe {eeper makes contact with the poles of the magnet and is normally held there by said magnet during the time when the switch is closed. When -air is admittedunder the piston 48, by opening of the valve 40, as when :the rise of pressure causes the diaphragm 21 to lift the stem 41 away from the valve end of the stem 33, the piston will be moved upwardly in the bore 49, the first portion of its movement will compress the spring quent intervals.

contact with the magnet. As soon as actual contact. is broken the spring 72 will then further move the keeper 77 with a quick snap-like movement and with lit the plug 66,

"thereby opening the circuit between the carbon blocks 55 and 56. lVhen the diaphragm 21 moves downwardly, as by the spring 45` as a. result of deer-ease of air pressure, the parts will again assume their respective po` sitions, shown in Fig. 2, and the switch will be again closed and the motor thereby started to increase the pressure. If the stem 33 were rigidly stationary it would require but very little variation in pressure to open and close ,the valve 40 and the motor would be started and stopped at unnecessarily fre- To avoid this I provide lost motion movement of the stem 33 by per# mitting the head 34 thereof to move within the space between .the shoulder 36 in the plug 28 and the adjustable plug 29. The greater this space the greater will be the variation of pressure permitted before the switch will be operated.

lA spring 80 serves to hold the plug 66 in an elevated position on the rod with reference to the nut 81, so that said plug may be adjusted to position where 1t will be in contact with the blocks 55 and 56 when the keeper 77 is seated on the magnet. The nut 68 is tapered at its upper edge and springs 82 and 83 carrying rollers 8 4 and 85 respectively are secured to opposlte sides of the casing as at 86 and 87 by screws 53. The rollers bear upon the tapered surfae of the .nut and serve to press the plug 66 v more firmly into -contact with the segment electrodes 55 and 56. When the nut 68 is raised, as when the switch is open the rollers ride on theI outer parallel surface ofy the nut and offer very little resistance to` means for elevating the plug 66. v

While I have herein described a singleV embodiment of my invention for purposes of complete disclosure, it is evident that departure may be made from the specific showing and within the scope of the appended claims without avoiding same.

What I claim is:

1. In a device of the character described, the combinationof a diaphragm, a valve controllable ythereby comprising a member movable with the diaphragm and a member with respect to which the diaphragm moves, said second member. being mounted to permitV lost motion thereof, and means whereby said second member is carried with said diaphragm-moved member in either 1,118,1sew

direction tothe 'extent permitted by said,

ldst motion. f

2. \In a device of the character described, a d1aphragm, a valve, and meansfor .con-v trol'of the latter by theformer comprising connections therebetween having parts asso ciated for initial non-effective Vlostmotion vi upon movement of the diaphragmin 'either direction, one of said parts being adjustable to vary the extent of saidnonfe'ective lost motion fof the diaphragm either direction.

L 3. Inral deviceI of the character described,

" one .tliereo the combination of a daphragm,\'a' v alve controllable thereby Acomprising' vrelatively movable seat and-,valve members, said mem! bers having portions .frictionally engaging,

phragm ried in saidcentral .perforationof thediaf phragmand the.' inner projecting through said 'perforation withinsaid diaphragm-carried .me1'11ber ,v said inner member being shaped to permit passag ofluidunder member', and means toivspport said inner member permitting lostqnotion for' move l ment thereowith the outer member in either directiofm acting valve `member provided with alatplug adjustable in said casing, mida'secjond' plug adjustable with re the valvemember beingvincluded ybetween said two. adjustable plugs', whereby topto- 4limits of which are adjustable.' l f .Intestimony whereof I'hereunto set'my hand in thev presence ofv two witnesses. ,1; .e A VfJOHN DEsMoND.- '-t e, resell/ceo e W.pL 1NN\-ALLEN, Jj-Z et mitsamt. said plug, said-'laterally projectingpart of 'e 45 pressure through said diaphragm-carried 5. The combination withadiaphragxnand l diaphragmarried valve'member, 'of 'a'co-v .4o 5' erally projecting partya 'ca'singz-inemb'ena vide lost-motion for said-'valve member the I 

